Paper gripping device for use with a chain driven paper carriage

ABSTRACT

Paper gripping device for use with a chain driven paper carriage comprising a gripper bar mounted between the driving chains of the paper carriage, the gripper bar having a U-shaped configuration where one leg of the U-shaped bar is stepped at the upper extremity thereof to form an inner, lower step and an outer, higher step; a shaft rotatably mounted in and along the length of the gripper bar; grip members mounted on the shaft; springs for respectively biasing the group members against the lower step of the stepped portion of the gripping bar so that when a paper sheet is gripped by the gripping member an outwardly convex configuration is imparted thereto by the upper step of the stepped portion to thereby facilitate subsequent processing of the paper; and cam means for rotating the grip members away from the lower step against the biasing action of the springs to permit reception or release of the paper away from the paper gripping device.

United States Patent [191 Murakami Dec. 9, 1975 PAPER GRIPPING DEVICE FOR USE WITH A CHAIN DRIVEN PAPER CARRIAGE [30] Foreign Application Priority Data Apr. 26, 1973 Japan 48-49277 [52] US. Cl. 271/277; 271/204 [51] Int. Cl. B65H 29/04 [58] Field of Search 271/82, 85, 204, 206, 277;

[56] References Cited UNITED STATES PATENTS 3,797,929 3/1974 Deacon et al 271/277 Primary ExaminerRichard A. Schacher Assistant ExaminerRobert Saifer Attorney, Agent, or Firm-Gerald J. Ferguson, Jr.; Joseph J. Baker [57] ABSTRACT Paper gripping device for use with a chain driven paper carriage comprising a gripper bar mounted between the driving chains of the paper carriage, the gripper bar having a U-shaped configuration where one leg of the U-shaped bar is stepped at the upper extremity thereof to form an inner, lower step and an outer, higher step; a shaft rotatably mounted in and along the length of the gripper bar; grip members mounted on the shaft; springs for respectively biasing the group members against the lower step of the stepped portion of the gripping bar so that when a paper sheet is gripped by the gripping member an outwardly convex configuration is imparted thereto by the upper step of the stepped portion to thereby facilitate subsequent processing of the paper; and cam means for rotating the grip members away from the lower step against the biasing action of the springs to permit reception or release of the paper away from the paper gripping device.

3 Claims, 5 Drawing Figures Sheet 2 0f 2 3,924,849

US. Patent Dec. 9, 1975 PAPER GRIPPING DEVICE FOR USE WITH A CHAIN DRIVEN PAPER CARRIAGE CROSS REFERENCE TO RELATED APPLICATION This application is related to a United States Patent Application entitled Improved Paper Feed Apparatus filed by Shin-ichi Murakami on Jan. 29, 1974, assigned Ser. No. 437,186 which is incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention This device relates to a gripper mechanism for carrying the sheets of paper one by one successively in a copying machine, printing machine or the like.

2. Discussion of the Prior Art Heretofore, roller or belt systems have been popularly used for passing the copy or printing paper through each process in a copying or printing machine. However, instead of such roller or belt systems, chain driven systems provided with gripper means adapted to grip or hold each sheet of paper have also been used for carrying the paper in a positive manner.

However, conventional chain-gripper systems have had many problems in practice. For example, the grippers mounted on the drive chain have been unduly large thus requiring excessive space therefor. Further, they have often failed to provide sufficient and uniform gripping force along the entire length of the paper. Also, the gripped end of the paper has tended to curl and undulate thus badly spreading ink or rendering it very difficult to transfer a perfect image onto the copy or printing paper. It has also been difficult to enable the grippers to grip the leading edge of the paper evenly along the entire length thereof.

SUMMARY OF THE INVENTION The present invention has a primary object of providing an improved chain gripper mechanism which avoids the above described problems of conventional systems.

Other objects and advantages of the invention will become apparent after reading the specification and claims taken with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic illustration of a copying machine in which the paper gripper of the present invention can be incorporated.

FIGS. 2 to illustrate a preferred embodiment of a paper gripper according to the present invention, where FIG. 2 is a plane view, FIG. 3 is a rear view, FIG. 4 is a sectional view taken along the line 44 of FIG. 2, and FIG. 5 is a partial, diagrammatic sketch illustrating the operation of the gripper.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Formation of the images on the surface of photoconductive drum 7 can be accomplished by known electrophotographic systems such as, for example, a xerographic system.

Copy paper is supplied from one of the paper trays 8 or 9 by a feed roller 10 or 11 and is carried to a transfer zone 14 by a gripper 13 provided on a chain 12. There the paper is closely attached to the surface of the photoconductive drum 7, with the image on the drum surface being transferred to the paper. Thereafter, the copy paper, to which the images have now been transferred, is carried through a fixing unit 15 to complete image fixing. It is then discharged into a receiver container 16. In the above process, the gripper 13 must securely grip every sheet of paper supplied by feed rollers 10 or 11.

Referring to FIGS. 2-5, an illustrative embodiment of a gripper mechanism according to the presentinvention is provided between two parallelchains 20 and 21 by brackets 34. A shaft 25 is rotatably supported by bearings 23 and 24 in a gripper bar 22 which is U- shaped in section. A plural number of gripping members 26 are rotatably mounted on shaft 25 at suitable intervals. Each of the gripping members 26 has a stopper portion 26a for registering the leading edge of paper P and a gripping 26b for holding paper P against an end of the gripper bar 22. Each gripping member 26 is forced in the gripping direction, that is, in the clockwise direction in FIG. 4, by an associated spring 27 provided on shaft 25.

In the inside of each gripping member 26 is provided a cam block 28 secured to shaft 25 so as to be rotated therewith and upwardly force gripping member 26, when required, to effect receiving or releasing of paper P. Rotation of shaft 25 is effected by operating a lever 29 at each end of shaft 25 by a cam 31 or other means.

The forward end 30 of U-sectioned gripper bar 22 is stepped (see FIG. 4) so that paper P is gripped by gripping member 26 at the inside lower step 30a of stepped portion 30. The paper P, when gripped, has imparted thereto an outwardly convex configuration by an outside higher step 30b. This convexity proves helpful to effect perfect intimate contact of the leading end of paper P against the surface of the photoconductive drum 7 in transfer zone 14 of FIG. 1.

Opening'and closing of each gripper member 26 is accomplished by displacing lever 29 with cam 31 as shown in FIG. 5. That is, when paper P is delivered along a guide 33 by feed rollers 32, the gripper 13, which operates at a faster speed than the paper delivery speed, registers the leading edge of paper P against its stopper portion 26a where the forward gripping portion 26b of gripping member 26 extends through an opening (not shown) in guide 33. A suitable paper feed device for use with the present invention is described in the copending application mentioned hereinbefore entitled Improved Paper Feed Apparatus." When lever 29 passes a point A on cam 31, gripper member 26 is closed to grip the paper P. Releasing of the grip can be accomplished in the same way by displacing the lever 29 by another cam or other means.

In summary, the chain driven, paper carriage gripper device according to the present invention provides a uniform gripping force spring 27 which independently press the respective gripper member 26. Registration or correct positioning of each sheet of paper P is readily accomplished as is imparting thereto an optimum configuration. Thus perfect image transfer to the very edge of paper P is effected and hence the attainment of high-quality reproductions.

What is claimed is:

1. Paper gripping device for use with a chain driven paper carriage having at least two driving chains comprising a gripper bar mounted between the driving chains of the paper carriage, said gripper bar having a U- shaped configuration where one leg of the U- shaped bar is stepped at the upper extremity thereof to form an inner, lower step and an outer, higher step having a rise therebetween;

a shaft rotatably mounted in and along the length of said gripper bar; grip members mounted on said shaft;

springs for respectively biasing said grip members against said inner, lower step of the stepped portion of the gripping bar, said grip members engaging said lower step substantially adjacent to the said rise from said inner, lower step to said outer, higher step so that when a paper sheet is gripped by said gripping member an outwardly convex configuration is imparted thereto by the upper step of said stepped portion to thereby facilitate subsequent processing of said paper; and

cam means for rotating said grip members away from said lower step against the biasing action of said springs to permit reception or release of said paper away from said paper gripping device.

2. A paper gripping device as in claim 1 where each of said grip members includes an upper, forwardly extending portion which engages said lower step under the biasing action of its associated spring and a lower, downwardly extending stopper portion against which said paper is registered as it is received by said paper gripping device.

3. A paper gripping device as in claim 2 including first cam members mounted in alignment with each other along said shaft for respectively raising said grip members away from said lower step; at least one lever mounted on said shaft; and a further cam member disposed adjacent the path traveled by said grip members for rotating said lever to effect said raising of the grip members through said first cam members. 

1. Paper gripping device for use with a chain driven paper carriage having at least two driving chains comprising a gripper bar mounted between the driving chains of the paper carriage, said gripper bar having a U-shaped configuration where one leg of the U-shaped bar is stepped at the upper extremity thereof to form an inner, lower step and an outer, higher step having a rise therebetween; a shaft rotatably mounted in and along the length of said gripper bar; grip members mounted on said shaft; springs for respectively biasing said grip members against said inner, lower step of the stepped portion of the gripping bar, said grip members engaging said lower step substantially adjacent to the said rise from said inner, lower step to said outer, higher step so that when a paper sheet is gripped by said gripping member an outwardly convex configuration is imparted thereto by the upper step of said stepped portion to thereby facilitate subsequent processing of said paper; and cam means for rotating said grip members away from said lower step against the biasing action of said springs to permit reception or release of said paper away from said paper gripping device.
 2. A paper gripping device as in claim 1 where each of said grip members includes an upper, forwardly extending portion which engages said lower step under the biasing action of its associated spring and a lower, downwardly extending stopper portion against which said paper is registered as it is received by said paper gripping device.
 3. A paper gripping device as in claim 2 including first cam members mounted in alignment with each other along said shaft for respectively raising said grip members away from said lower step; at least one lever mounted on said shaft; and a further cam member disposed adjacent the path traveled by said grip members for rotating said lever to effect said raising of the grip members through said first cam members. 